Trailer Abs Wiring Diagram | Trailer Wiring Diagram Wabco Abs Schematic – Wiring Diagrams Hubs – Trailer Abs Wiring Diagram by Bismillah. 7-Pin Connector; This Trailer Abs Wiring Diagram version is much more appropriate for sophisticated trailers and RVs. It may transfer power better so the connector is suggested for higher-level electric in the auto. Trailer Wiring Diagrams | etrailer Trailer Wiring Diagrams. 7-Way Round Trailer Connector (Round Pin) 7-Way Round Vehicle Connector (Round Pin) Note: To ensure that your trailer connector is wired properly, we recommend using a circuit tester to match pins by function. Because wire colors can vary, they are ISO standards for trailer connectors - Wikipedia ISO standards for trailer connectors 7-pin trailer connector for ABS/EBS (ISO 7638-2) part here is that pin 5 is used for trailer brake which means that if you for some reason connect an Australian trailer to a towing vehicle with ISO wiring you will get into trouble with the trailer brakes being applied as soon as you turn on the Trailer Wiring Diagram – Lights, Brakes, Routing, Wires In the Trailer Wiring Diagram and Connector Application Chart below, use the first 5 pins, and ignore the rest. If your truck has a built-in 7-pin socket, but you only need 5 of the pins. Use the 7-pin connector anyway (see below), and just leave out the last 2 wires.